KR101198787B1 - Exhaust gas post processing system and control method thereof - Google Patents

Abstract

Exhaust gas post-treatment method according to an embodiment of the present invention, exhaust gas post-treatment method according to the present invention, if the temperature difference (ΔT) before and after the catalyst during injection of the reducing agent is the reference temperature difference (X) or less of the catalyst Desulfurization regeneration by raising the temperature to the set value, determining whether the mileage after desulfurization regeneration, fuel consumption, or running time exceeds the set first reference value, and determining that the fuel has been replenished using the replenished amount of fuel. And the first reference value does not exceed the set reference value, and it is determined that fuel is replenished, and the catalyst is abnormally desulfurized and regenerated if the temperature difference ΔT is equal to or less than the reference temperature difference X while injecting a reducing agent. Step, counting the number of abnormal desulfurization regeneration, and if the number of abnormal desulfurization of the catalyst is more than the set value, a warning signal that high sulfur fuel is injected And a step of generating.
Therefore, during the nitrogen purifying mode to purify the nitrogen oxides, desulfurization control is performed according to the temperature difference between the front and rear ends of the catalyst, and when abnormal desulfurization control is repeatedly performed, it is determined that high sulfur fuel is injected. Can be. Therefore, the vehicle driver may easily determine the injection of the high sulfur fuel, and may guide the vehicle driver to prevent the high sulfur fuel from being injected later.

Description

Exhaust gas aftertreatment system and its control method {EXHAUST GAS POST PROCESSING SYSTEM AND CONTROL METHOD THEREOF}

The present invention relates to an exhaust gas aftertreatment system and a control method thereof, and more particularly, to an exhaust gas aftertreatment system having a nitrogen oxide purification catalyst for removing nitrogen oxide contained in exhaust gas and a control method thereof.

In systems using diesel fuel, the main purpose of exhaust aftertreatment is to reduce particulate matter and remove nitrogen oxides.

Diesel particulate filter (DPF) is used to reduce particulate matter, and nitrogen oxide purification catalyst (LNT) is used to remove nitrogen oxides.

Since the diesel particulate filter and the nitrogen oxide purification catalyst are contaminated by sulfur components contained in the exhaust gas, and the performance thereof is degraded, desulfurization regeneration is performed by periodically raising the temperature using a secondary injection system. Should be.

On the other hand, when the high sulfur fuel is injected, the diesel particulate filter or the nitrogen oxide purification catalyst is frequently regenerated, and the durability thereof is drastically reduced or frequent desulfurization regeneration causes a problem of increased fuel consumption.

Accordingly, the present invention provides an exhaust gas after-treatment method for notifying injection of high-sulfur fuel so as to increase the durability of the catalyst to be desulfurized and regenerated, such as a diesel particulate filter or a nitrogen oxide purification catalyst installed in an exhaust line, and to reduce fuel consumption. It is.

In the exhaust gas post-treatment method according to the present invention, if the temperature difference (ΔT) at the front and rear ends of the catalyst is lower than or equal to the reference temperature difference (X) during the injection of the reducing agent, the desulfurization regeneration is carried out by raising the temperature of the catalyst to a set value. Determining whether the mileage, fuel consumption, or travel time has exceeded the set first reference value; determining that fuel has been replenished using the supplemented amount of fuel; and wherein the first reference value does not exceed the set reference value. When the fuel is replenished and the temperature difference ΔT is less than or equal to the reference temperature difference X while injecting a reducing agent, abnormally desulfurization regeneration of the catalyst, counting the number of abnormal desulfurization regeneration, and And generating a warning signal that the high sulfur fuel is injected when the number of abnormal desulfurization of the catalyst is greater than or equal to a set value.

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As described above, in the exhaust gas aftertreatment method according to the present invention, while performing the nitrogen purification mode to purify the nitrogen oxide, desulfurization control is carried out according to the temperature difference between the front and rear of the catalyst, and abnormal desulfurization control is repeatedly performed. If performed, it may be determined that high sulfur fuel is injected.

Therefore, the vehicle driver may easily determine the injection of the high sulfur fuel, and may guide the vehicle driver to prevent the high sulfur fuel from being injected later.

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.
Figure 2 is a graph showing the difference between the reducing agent injection amount and the front and rear end temperature difference in the exhaust gas after-treatment system according to an embodiment of the present invention.
3 is a flowchart illustrating an exhaust gas post-treatment method according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic configuration diagram of an exhaust gas aftertreatment system according to an embodiment of the present invention.

Referring to FIG. 1, the exhaust gas aftertreatment system includes an engine 100, an injector 150, a diesel fuel catalyst 120, a diesel particulate filter 130, a nitrogen oxide purification catalyst 140, and a first oxygen sensor OS1. , A second oxygen sensor OS2, a fourth temperature sensor TS4, a fifth temperature sensor TS5, a sixth temperature sensor TS6, a seventh temperature sensor TS7, and a controller 110.

The diesel fuel catalyst 120 (DFC: diesel fuel cracking), the diesel particulate filter (130, DPF: diesel particulate filter), and the nitrogen oxide purification catalyst 140 are sequentially disposed in an exhaust line, and the diesel fuel catalyst ( The injector 150 is installed upstream of the injector 120, and the first oxygen sensor OS1 is disposed upstream of the injector 150. In addition, the second oxygen sensor OS2 is disposed downstream of the nitrogen oxide purification catalyst 140.

The fourth temperature sensor TS4 is disposed between the injector 150 and the diesel fuel catalyst 120, and the fifth temperature sensor between the diesel fuel catalyst 120 and the diesel particulate filter 130. TS5) is arranged.

The sixth temperature sensor TS6 is disposed between the diesel particulate filter 130 and the nitrogen oxide purification catalyst 140, and between the nitrogen oxide purification catalyst 140 and the second oxygen sensor OS2. The seventh temperature sensor TS7 is disposed.

The control unit 110 may include the first oxygen sensor OS1, the injector 150, the fourth temperature sensor TS4, the fifth temperature sensor TS5, and the sixth temperature sensor functioning as a detection unit. TS6), the seventh temperature sensor TS7, and the second oxygen sensor OS2 are electrically connected to each other, and receive a signal detected by the detector.

The controller 110 determines a time for regenerating the diesel fuel catalyst 120, the diesel particulate filter 130, or the nitrogen oxide purification catalyst 140, and controls the injector 150 to control a reducing agent. Spray.

The first oxygen sensor OS1 and the second oxygen sensor OS2 detect the concentration of oxygen included in the exhaust gas, and based on the detected signal, the controller 110 determines the state of the exhaust gas. do.

The fourth temperature sensor TS4 detects the temperature of the exhaust gas at the front end of the diesel fuel catalyst 120, and the fifth temperature sensor TS5 is the rear end of the diesel fuel catalyst 120 and the diesel particulate smoke. The temperature of the exhaust gas of the front end of the filter 130 is sensed.

The sixth temperature sensor TS6 detects the temperature of exhaust gas at the rear end of the diesel particulate filter 130 and the front end of the nitrogen oxide purification catalyst 140, and the seventh temperature sensor TS7 is the nitrogen. The temperature of the exhaust gas at the rear end of the oxide purification catalyst 140 is sensed.

While the reducing agent is injected from the injector 150, the controller 110 controls the temperature difference between the front and rear ends of the diesel fuel catalyst 120 through the temperature sensors TS4, TS5, TS6, and TS7. The front and rear end temperature difference of the soot filter 130 and the front and rear end temperature difference of the nitrogen oxide purification catalyst 140 are respectively calculated.

The controller 110 detects the concentration of the injected reducing agent and controls the injection amount according to the oxygen value detected by the first oxygen sensor OS1 and the second oxygen sensor OS2.

The controller 110 may be implemented as one or more microprocessors operated by a set program, and the set program may be configured to perform each step included in the deceleration control method of the automatic transmission vehicle according to the embodiment of the present invention described below. It can be a series of instructions.

Figure 2 is a graph showing the difference between the reducing agent injection amount and the front and rear end temperature difference in the exhaust gas after-treatment system according to an embodiment of the present invention.

Referring to FIG. 2, the horizontal axis represents the amount of reducing agent injected from the injector 150, and the vertical axis represents the temperature difference between the front and rear ends of the catalyst. In an embodiment of the present invention, a catalyst may be applied to the diesel fuel catalyst 120, the diesel particulate filter 130, or the nitrogen oxide purification catalyst 140.

According to the amount of reducing agent injected from the injector 150, the temperature difference between the front and rear of the catalyst forms a constant pattern, which is a value stored in a preset memory. On the other hand, when the catalyst deteriorates and does not exhibit normal performance, the front and rear temperature difference decreases.

The causes of the decrease in the temperature difference between the front and rear ends of the catalyst are largely divided into normal cases and abnormal cases. Normal cases include a case in which a mileage, a fuel consumption amount, or a running time exceeds a set value, and a substance such as sulfur accumulates. In an abnormal case, the temperature sensor TS4, TS5, TS6, TS7, or the injector 150) has failed.

In particular, when the diesel fuel contains a high concentration of sulfur components, the catalyst is rapidly contaminated by sulfur, and while the reducing agent is injected, the catalyst does not operate normally and the front and rear temperature differences are drastically reduced.

3 is a flowchart illustrating an exhaust gas post-treatment method according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in S300, a nitrogen oxide purification mode is performed to remove nitrogen oxides from the nitrogen oxide purification catalyst 140. In the nitrogen oxide purification mode, fuel is injected from the injector 150 as a reducing agent, and the injected reducing agent and the diesel fuel catalyst 120 react to activate the reducing agent.

In addition, the activated reducing agent reacts with the nitrogen oxide purification catalyst 140 to remove nitrogen oxide trapped in the nitrogen oxide purification catalyst 140.

In S312, the amount of fuel is sensed, and in S310, it is determined whether the front and rear temperature difference ΔT of the catalyst is larger than the reference temperature difference X, and when the front and rear temperature difference ΔT is larger than the reference temperature difference X, the NOx purification mode is normally If the front and rear temperature difference ΔT is less than or equal to the reference temperature difference X, S320 is performed.

In S320, the desulfurization mode is performed, and the injector 150 is further injected with a reducing agent to further increase the temperature of the catalyst.

In S330, immediately after desulfurization, it is determined whether the front and rear temperature difference ΔT of the catalyst is greater than the reference temperature difference X, and if the front and rear temperature difference ΔT is larger than the reference temperature difference X, S300 is performed and the front and rear temperature difference ( If ΔT) is less than or equal to the reference temperature difference X, S340 is performed.

In S340, it is determined whether the fuel is replenished. The controller 110 detects the amount of fuel from the fuel gauge, and determines whether the fuel is replenished from the detected amount of fuel.

If the fuel has not been replenished, S350 is performed to determine whether there is an abnormality of the catalyst or the injector 150, and a troubleshooting is performed in S360. In the embodiment of the present invention, a method for determining the abnormality of the catalyst or the injector 150 is omitted.

When the fuel is replenished, the state of the catalyst or the injector 150 is checked in S270, and S380 is performed.

In step S380, it is determined whether the driving distance after desulfurization is equal to or greater than a desulfurization standard operating distance. In an embodiment of the present invention, in S380, it is determined whether the running time after desulfurization is greater than the desulfurization reference running time.

In an embodiment of the present invention, in step S380, it is possible to determine whether the fuel consumption after desulfurization is more than the desulfurization standard fuel consumption instead of the driving distance. That is, in S380, it is determined whether the running distance, running time, or fuel consumption amount accumulated after desulfurization performed in S320 is greater than or equal to a set value.

In S380, if the driving distance, the running time, or the fuel consumption amount is greater than the set value after desulfurization, S320 is performed.

After desulfurization, the operating distance, running time, or fuel consumption amount is less than the set value, but as determined in S330, since the front and rear temperature difference ΔT of the catalyst is equal to or less than the reference temperature difference X, abnormal desulfurization is performed in S390. To perform the S320 to perform, in this way, counts the number of times the abnormal desulfurization was performed.

In step S390, counting the number of times the abnormal desulfurization is performed, and if the number is two times, in S400, it is determined that the natural sulfur fuel is injected, and displays an alarm to the driver.

As described above, while performing the nitrogen purification mode to purify the nitrogen oxides using the nitrogen oxide purification catalyst, desulfurization control is performed according to the front and rear temperature difference of the catalyst, and abnormal desulfurization control is repeatedly performed. If it is, it can be determined that the high sulfur fuel is injected.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, And all changes to the scope that are deemed to be valid.

100: engine
110: control unit
120: diesel fuel cracking (DFC)
130: diesel particulate filter (DPF: diesel par)
140: nitrogen oxide purification catalyst
150: injector
OS1, OS2: First and second oxygen sensor
TS4, TS5, TS6, TS7: 4th, 5th, 6th, 7th temperature sensor

Claims (4)

Desulfurization regeneration by raising the temperature of the catalyst to a set value when the temperature difference ΔT of the front and rear ends of the catalyst is equal to or less than the reference temperature difference X while the reducing agent is injected;
Determining whether the mileage, fuel consumption, or travel time after the desulfurization regeneration has exceeded the set first reference value;
Using the replenished amount of fuel, determining that the fuel has been replenished;
Abnormal desulfurization regeneration of the catalyst when the first reference value does not exceed the set reference value and the fuel is determined to be replenished, and the temperature difference ΔT is equal to or less than the reference temperature difference X while injecting a reducing agent;
Counting the number of abnormal desulfurization regeneration; And
Generating a warning signal that high sulfur fuel is injected when the number of abnormal desulfurization of the catalyst is equal to or greater than a set value; And the exhaust gas after-treatment. delete A catalyst for removing particulate matter contained in exhaust gas;
A detector for detecting a driving state of the vehicle; And
A control unit which performs the method according to claim 1 for regenerating the catalyst according to the driving conditions of the vehicle sensed by the detection unit; Exhaust gas aftertreatment system comprising a. 4. The method of claim 3,
The catalyst is,
Oxidation catalyst to remove harmful substances contained in exhaust gas,
Diesel particulate filter for trapping particulate matter contained in exhaust gas, or
An exhaust gas aftertreatment system, comprising: a nitrogen oxide purification catalyst for removing nitrogen oxides contained in exhaust gas.

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